Iridium tricks (was Re: Iridium Flares ground projection)
J.C. Millot (papou@canl.nc)
Wed, 4 Feb 1998 12:20:44 +1100
Hi all,
Two remarks about Iridium flares that you may find useful.
About shadows
>> does venus cast visible shadows? i've heard of bright meteors
>> (-8, -10 range i would assume) casting them. who knows? so who among you
>> is going to be the first to turn your back on a monster-flare to look for
>> your shadow?
>
>I've seen shadows cast by Venus. On a recent Iridium flare (magnitide
>-5.6) I turned my back to look on the ground but saw nothing. I think it
>would be quite difficult!
>
>It was easier (for Venus) to be inside a dark room & see the patch of
>light moving slowly across the wall. Once you found the patch of light,
>it was fairly easy to make a shadow. The same trick would be hard for a
>short-duration Iridium flare!
>
>Best, Mark
>--
>Mark Hanning-Lee, markhl@prodigy.net
>
I used this following trick to see a shadow cast by Jupiter at opposition
(It was mag -2.5 I think).
Put on a white T-shirt or sweatshirt.
Wait for Jupiter to be at an altitude of 45 degrees or so.
Put your hand in front of you so that Jupiter can cast a shadow on your
T-shirt.
Of course now you will have to wait for the same sort of conditions with
Iridiums satellites.
Another trick to compare magnitude of a crescent moon and a bright Iridium
flare:
take a low power pair of binoculars and look at the moon through the wrong
side of the binocs. The moon should be concentrated to something looking
more like a dot than with one power. Try different powers of binoculars.
Try to look a Venus too with these binoculars(Mag -5)
The 7 day moon is said to be mag -9 I think.
Then imagine the middle of these two bightness and you get mag -7.
Then imagine some brightness in the middle of -5 to -7 and you get -6, same
thing for -8.
If you have a bright light away from you about this bright like a spot or a
lighthouse this could help too because it will be there even if Venus and
the Moon are not present in the sky.
So practice now and then get ready for the monster flare.
Than be ready for you bright Iridium flare with the same binocs. I find it
easy to compare. My best one is mag -8 up to now.
Hope this helps.
Of course, any remarks about these methods are welcome.
Jean-Christophe 'Papou' Millot - email : papou@canl.nc
Consultant en Technologies de l'Information - IT Consultant
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